ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 339 



them is the length of hyphre that intervenes between the catenulate 

 spores, and the muriform character of the spores in Alter naria as com- 

 pared with the transverse divisions in the spores of Polydesmus. 

 Voglino proves that the distinction breaks down and that the two 

 forms are really one and the same, and ought to be united under the 

 earlier name Altemaria Brassicce. He demonstrated also the parasitic 

 nature of the fungus. It causes a troublesome disease on several forms 

 of Brassica. 



Schizophyta. 

 Schizophycese. 



Floating Properties of certain Phycochromaceae.* — H. Molisch has 

 examined certain species of this group of algae, notably Aphanizomenon 

 jios-aqim, and comes to the conclusion that the view held by authors as 

 to the nature of the red bodies in many of the cells is not correct. It 

 has been considered by Strodtmann, Klebahn, and others that these 

 bodies are gas-vacuoles, since when they are present the algae float on 

 the surface of the water, and when they are artificially removed the 

 same algae sink to the bottom. The present author gives reasons, 

 founded on his own investigations, to show that these floats (Schwebe- 

 korper) are not gas-vacuoles, but seem rather to consist of a more or 

 less viscous substance inclosed in a delicate membrane. If this view be 

 correct, it is easy to explain the result of certain experiments detailed 

 here. The author is inclined to believe that the so-called sulphur-grains 

 or gas-vacuoles of Thiothrix tenuis are bodies of the same more or less 

 viscous substance. 



Schizomycetes. 



Physiology of Spore-formation in Bacteria.f — Matzuschita has 

 made observations on the effect of external conditions upon endogenous 

 spore-formation, especially in anaerobes. The general result obtained 

 was that to all changes of external conditions, such as concentration of 

 medium, temperature and pressure, addition of noxious substances, 

 spore-formation was more sensitive than growth. 



Bacterial Origin of Vegetable Gums.J — R. Grieg Smith, of Sydney, 

 has been led by his previous work on the gums and slimes produced 

 by bacteria, to investigate other gums which are supposed to be the 

 secretions of higher plants. Gum acacia was investigated. From 

 Acacia hinervata a bacterium was separated which in artificial media 

 produced a slime which yielded a gum giving all the reactions of gum 

 acacia. There can thus be no doubt that this gum is of bacterial origin. 

 The bacterium, to which the name B. Acacia, was given, is rod-shaped, 

 measures • 5-0 • 6 by ' 5-2 yu, is not stained by Gram's method, and 

 has one to many peritrichous flagella. It is aerobic and produces no 

 spores ; it grows at 37° C, but most slime is produced at 15°-22° C. 

 From Acacia penninervis there were isolated two bacteria, one, B. Acacice, 



* Bot. Zeii, 1903, pp. 47-5S (4 figs, in text). 



t Arch. f. Hygiene, xliii. p. 267. See also Centralbl. Bakt., x. (1903) pp. 123-5. 

 t Proc. Linn. Soc. N.S. Wales, 1902, pt. 3. See also Centralbl. Bakt., x. 

 <1903) pp. 61-3. 



